1. Field of the Invention
The present invention relates to a paper feeder in a recording apparatus such as a copying machine, a laser beam printer or the like and, more particularly, to a paper feeder which has a plurality of paper feed sources which may be automatically changed.
2. Description of the Prior Art
A conventional paper feeder for an image recording apparatus such as an electrophotographic copying apparatus is known wherein a plurality of paper feed sources are automatically changed. More specifically, a paper feeder which has two paper feed sources or two cassettes is known. In this paper feeder, only if the paper sheet sizes are the same, the paper sheets in the second cassette are fed when the first cassette is empty.
A paper feeder of the type as described above is conventionally used in a copying machine with a plurality of paper feed sources. A method has been proposed wherein, when a paper feed source is empty, paper sheets of the same size are continuously fed from another paper feed source. However, various types of paper sheets are recently used in recording apparatuses such as printers or copying machines, which include color paper sheets, drawing copying paper sheets, transparent sheets, label paper sheets, and format paper sheets in addition to general white sheets. Furthermore, paper sheets of the same size may be fed along their short sides or long sides. Assume that automatic changing of paper feed sources is performed by discriminating only the size of the paper sheets in a recording apparatus. If general paper sheets are stored in a first paper feed source, if drawing copying paper sheets of the same size as that of the general paper sheets are stored in a second paper feed source, and if an "empty state" of the first paper feed source is detected during the paper feeding operation, the recording paper sheets are inadvertently changed from the general paper sheets to the drawing copying paper sheets. This results in waste of the drawing copying paper sheets. If automatic changing is made between paper feed sources of different feeding directions, all the information may not be recorded completely.
This not only results in extra work on the side of the operator but also in waste of paper sheets.